1. Field of the Invention
The present general inventive concept relates to an image forming apparatus, and more particularly to an image forming apparatus which includes a printing medium guide device to guide a printing medium toward a discharge path or a reverse path in a duplex printing operation.
2. Description of the Related Art
The image forming apparatuses, such as laser printers or copying machines, include a duplex image forming apparatus. The duplex image forming apparatus can print an image on both surfaces of a sheet of paper. Korean Patent Laid-open Publication No. 2007-0025051 relates to a conventional duplex image forming apparatus, which includes a print path to print the fed paper, a discharge path to discharge the printed paper, and a reverse path to turn over the paper, of which one surface has been printed, and feed the same again to the print path.
The conventional duplex image forming apparatus further includes a paper guide device which guides the paper, which has passed through a fusing unit in the print path, toward the discharge path, or guides the paper in the discharge path toward the reverse path in a duplex printing operation. The paper guide device is rotatably mounted in a junction point of the print path, the discharge path and the reverse path to convert the paper feeding path, and thus prevents a paper feeding error.
However, in the conventional image forming apparatus as structured above, because the paper guide device contacts a surface of the paper while guiding the paper feed, the paper guide device acts as a resistance to the paper feed, and a developer on the paper adheres to the paper guide device. Specifically, in the duplex printing operation, when the paper of which one surface has been printed passes again through the fusing unit, the developer fused to the previously-printed surface melts temporarily by heat while passing through the fusing unit, and adheres to the paper guide device. Then, the developer sticks to the paper guide device, and can continue to grow corresponding to the repetition of the printing, thereby interrupting the paper being feed in a smooth manner. For instance, the developer sticking to the paper guide device causes a scratch on the surface of the paper or paper jam.